The present invention relates generally to a platform for use in the construction industry and more particularly a multi-purpose platform for combining the lifting capabilities of two truck cranes or crawler cranes.
Most construction companies will have one or more general, all-purpose truck cranes or crawler cranes which are capable of lifting and moving the majority of loads encountered on a typical construction project. Occasionally, certain construction projects require that a load beyond the lifting capacity of the construction company's all-purpose cranes be lifted or moved. Presently, whenever this occurs, the construction company must purchase or lease a crane having a larger lifting capacity. For most companies, the additional cost of purchasing a larger capacity crane cannot be justified merely because an occasional construction project requires the use of a high-capacity crane.
Designers of lift cranes are faced with the conflicting requirements of creating a portable crane which may be easily transported to a work site, but also creating a high-capacity crane which has sufficient versatility to perform all the usual work site tasks. The ideal high-capacity crane would be capable of performing the daily functions of the smaller cranes while having the ability to lift heavier loads whenever necessary. At present, this ideal crane has not been designed.
One example of an attempt to create an inexpensive and mobile high-capacity crane is illustrated in U.S. Pat. Nos. 4,042,115 and 4,103,783 issued to Beduhn et al. on Aug. 16, 1977 and Aug. 1, 1978, respectively. The invention disclosed in these patents consists, in part, of a mobile transporter which is designed to provide a means for moving the high-capacity crane assembly to a work site without disassembling the entire crane structure. These patents describe the desirability of having the disclosed crane assembly constructed of standard subassemblies; however, this desired construction is described in the patents as being substantially more complex and expensive than the preferred embodiment of the present invention.
Another approach to this problem is disclosed in U.S. Pat. Nos. 4,449,635 and 4,601,402 issued to Helm et al. on May 22, 1984 and July 22, 1986, respectively. These patents disclose the use of a pair of crawler assemblies wherein the front assembly pivotally supports the mast and boom assemblies while the rear assembly pivotally supports the counterweight. The pair of assemblies are independently steerable and pivotally attached to each other by one or more frame elements.
The above-described patents are representative of various approaches that have been taken to create an inexpensive and versatile high-capacity crane. The present invention is directed to the use of a multipurpose platform which will enable a construction company to combine the lifting capabilities of existing equipment to create a high-capacity assembly, and thereby avoid the expense of having to purchase a high-capacity crane having limited usefulness in the company's day-to-day operations.